Wireless communication method and wireless communication terminal

ABSTRACT

Disclosed is a wireless communication terminal. The wireless communication terminal includes a transceiver transmitting/receiving a wireless signal; and a processor controlling an operation of the wireless communication terminal. The transceiver receives a first frame including information on a manner for accessing, by a plurality of wireless communication terminals including the wireless communication terminal, a base wireless communication terminal. The processor acquires a manner for accessing the base wireless communication terminal on a basis of the first frame. The transceiver accesses the base communication terminal on a basis of the manner for accessing the base wireless communication terminal. The base wireless communication terminal is any one communication terminal different from the plurality of wireless communication terminals.

TECHNICAL FIELD

The present invention relates to a wireless communication method and awireless communication terminal for setting a broadband link. Morespecifically, the present invention relates to a wireless communicationmethod and a wireless communication terminal for increasing datacommunication efficiency by expanding a data transmission bandwidth of aterminal.

BACKGROUND ART

In recent years, with supply expansion of mobile apparatuses, a wirelessLAN technology that can provide a rapid wireless Internet service to themobile apparatuses has been significantly spotlighted. The wireless LANtechnology allows mobile apparatuses including a smart phone, a smartpad, a laptop computer, a portable multimedia player, an embeddedapparatus, and the like to wirelessly access the Internet in home or acompany or a specific service providing area based on a wirelesscommunication technology in a short range.

Institute of Electrical and Electronics Engineers (IEEE) 802.11 hascommercialized or developed various technological standards since aninitial wireless LAN technology is supported using frequencies of 2.4GHz. First, the IEEE 802.11b supports a communication speed of a maximumof 11 Mbps while using frequencies of a 2.4 GHz band. IEEE 802.11a whichis commercialized after the IEEE 802.11b uses frequencies of not the 2.4GHz band but a 5 GHz band to reduce an influence by interference ascompared with the frequencies of the 2.4 GHz band which aresignificantly congested and improves the communication speed up to amaximum of 54 Mbps by using an OFDM technology. However, the IEEE802.11a has a disadvantage in that a communication distance is shorterthan the IEEE 802.11b. In addition, IEEE 802.11g uses the frequencies ofthe 2.4 GHz band similarly to the IEEE 802.11b to implement thecommunication speed of a maximum of 54 Mbps and satisfies backwardcompatibility to significantly come into the spotlight and further, issuperior to the IEEE 802.11a in terms of the communication distance.

Moreover, as a technology standard established to overcome a limitationof the communication speed which is pointed out as a weak point in awireless LAN, IEEE 802.11n has been provided. The IEEE 802.11n aims atincreasing the speed and reliability of a network and extending anoperating distance of a wireless network. In more detail, the IEEE802.11n supports a high throughput (HT) in which a data processing speedis a maximum of 540 Mbps or more and further, is based on a multipleinputs and multiple outputs (MIMO) technology in which multiple antennasare used at both sides of a transmitting unit and a receiving unit inorder to minimize a transmission error and optimize a data speed.Further, the standard can use a coding scheme that transmits multiplecopies which overlap with each other in order to increase datareliability.

As the supply of the wireless LAN is activated and further, applicationsusing the wireless LAN are diversified, the need for new wireless LANsystems for supporting a higher throughput (very high throughput (VHT))than the data processing speed supported by the IEEE 802.11n has comeinto the spotlight. Among them, IEEE 802.11ac supports a wide bandwidth(80 to 160 MHz) in the 5 GHz frequencies. The IEEE 802.11ac standard isdefined only in the 5 GHz band, but initial 11ac chipsets will supporteven operations in the 2.4 GHz band for the backward compatibility withthe existing 2.4 GHz band products. Theoretically, according to thestandard, wireless LAN speeds of multiple stations are enabled up to aminimum of 1 Gbps and a maximum single link speed is enabled up to aminimum of 500 Mbps. This is achieved by extending concepts of a radiointerface accepted by 802.11n, such as a wider radio frequency bandwidth(a maximum of 160 MHz), more MIMO spatial streams (a maximum of 8),multi-user MIMO, and high-density modulation (a maximum of 256 QAM).Further, as a scheme that transmits data by using a 60 GHz band insteadof the existing 2.4 GHz/5 GHz, IEEE 802.11ad has been provided. The IEEE802.11ad is a transmission standard that provides a speed of a maximumof 7 Gbps by using a beamforming technology and is suitable for high bitrate moving picture streaming such as massive data or non-compression HDvideo. However, since it is difficult for the 60 GHz frequency band topass through an obstacle, it is disadvantageous in that the 60 GHzfrequency band can be used only among devices in a short-distance space.

Meanwhile, in recent years, as next-generation wireless LAN standardsafter the 802.11ac and 802.11ad, discussion for providing ahigh-efficiency and high-performance wireless LAN communicationtechnology in a high-density environment is continuously performed. Thatis, in a next-generation wireless LAN environment, communication havinghigh frequency efficiency needs to be provided indoors/outdoors underthe presence of high-density stations and access points (APs) andvarious technologies for implementing the communication are required.

Especially, as the number of devices using a wireless LAN increases, itis necessary to efficiently use a predetermined channel. Therefore,required is a technology capable of efficiently using bandwidths bysimultaneously transmitting data between a plurality of stations andAPs.

DISCLOSURE Technical Problem

An object of an embodiment of the present invention is to provide anefficient wireless communication method and wireless communicationterminal.

In particular, a purpose of an embodiment of the present invention is toprovide a wireless communication method and wireless communicationterminal in which a plurality of wireless communication terminalssimultaneously transmit data to any one wireless communication terminal.

Technical Solution

A wireless communication terminal according to an embodiment of thepresent invention includes: a transceiver transmitting/receiving awireless signal, and a processor controlling an operation of thewireless communication terminal, wherein the transceiver receives afirst frame including information on a manner for accessing, by aplurality of wireless communication terminals including the wirelesscommunication terminal, a base wireless communication terminal, theprocessor acquires a manner for accessing the base wirelesscommunication terminal on a basis of the first frame, the transceiveraccesses the base communication terminal on a basis of the manner foraccessing the base wireless communication terminal, and the basewireless communication terminal is any one communication terminaldifferent from the plurality of wireless communication terminals.

The information on the manner for accessing the base wirelesscommunication terminal may include information on an orthogonal codeused for accessing, by the wireless communication terminal, the basewireless communication terminal, and the transceiver may access the basewireless communication terminal on a basis of the information on theorthogonal code.

The information on the orthogonal code may include information on aplurality of orthogonal codes, the processor randomly may select any oneof the plurality of orthogonal codes, and the transceiver may access thewireless communication terminal by using the selected orthogonal code.

The transceiver may transmit, to the base wireless communicationterminal, required information for allocating a channel to the wirelesscommunication terminal, receive a second frame indicating the channelallocated to the wireless communication terminal, and transmit data tothe base wireless communication terminal on a basis of the second frame.

Required information for allocating channels to the plurality ofwireless communication terminals may include information indicating asize of data to be transmitted by the wireless communication terminal tothe base wireless communication terminal.

Required information for allocating channels to the plurality ofwireless communication terminals may include information on idlechannels sensed by the wireless communication terminal.

Required information for allocating channels to the plurality ofwireless communication terminals may include an identifier foridentifying the wireless communication terminal.

The transceiver may transmit a third frame to the base wirelesscommunication terminal and then transmit meaningless dummy data.

The third frame may be a data frame including data.

The third frame may be a frame including required information forchannel allocation for the wireless communication terminal to the basewireless communication terminal.

The transceiver may repeatedly transmit an identical frame to the basewireless communication terminal.

The information on the manner for accessing the base wirelesscommunication terminal may include information on a time when thewireless communication terminal accesses the base wireless communicationterminal.

The information on the manner for accessing the base wirelesscommunication terminal may include information on a period that thewireless communication terminal accesses the base wireless communicationterminal.

The transceiver may receive, from the base wireless communicationterminal, a fourth frame for triggering an access to the base wirelesscommunication terminal and access the base wireless communicationterminal on a basis of the fourth frame.

A base wireless communication terminal according to an embodiment of thepresent invention includes: a transceiver transmitting/receiving awireless signal; and a processor controlling an operation of thewireless communication terminal, where the transceiver transmits, to aplurality of wireless communication terminals, a first frame includinginformation on a manner for accessing, by the plurality of communicationterminals, the base wireless communication terminal.

The transceiver may receive, from the plurality of wirelesscommunication terminals, required information for allocating channels tothe plurality of wireless communication terminals, and the processor mayallocate the channels the plurality of wireless communication terminalson a basis of the required information for allocating the channels tothe plurality of wireless communication channels, and transmit a frameindicating the channels allocated to the plurality of wirelesscommunication channels.

The required information for allocating the channels to the plurality ofwireless communication terminals may include information on idlechannels sensed by the wireless communication terminal.

The transceiver may receive a second frame from any one of the pluralityof wireless communication terminals and then receive meaningless dummydata from the any one wireless communication terminal.

The information on the manner for accessing the base wirelesscommunication terminal may include information on a period that theplurality of wireless communication terminals access the base wirelesscommunication terminal.

An operation method of a wireless communication terminal according to anembodiment of the present invention includes: receiving, by a pluralityof wireless communication terminals including the wireless communicationterminal, a frame including information on a manner for accessing a basewireless communication terminal; acquiring the manner for accessing thebase wireless communication terminal on a basis of a frame includinginformation on the manner for accessing the base wireless communicationterminal; and accessing the base communication terminal on a basis ofthe manner for accessing the base wireless communication terminal,wherein the base wireless communication terminal is any one wirelesscommunication terminal different from the plurality of wirelesscommunication terminals.

Advantageous Effects

An embodiment of the present invention provides an efficient wirelesscommunication method and wireless communication terminal.

In particular, an embodiment of the present invention provides awireless communication method and wireless communication terminal inwhich a plurality of wireless communication terminals simultaneouslytransmit data to any one wireless communication terminal.

DESCRIPTION OF DRAWINGS

FIG. 1 is a view illustrating a wireless LAN system according to anembodiment of the present invention.

FIG. 2 is a view illustrating a wireless LAN system according to anotherembodiment of the present invention.

FIG. 3 is a block diagram illustrating a configuration of a stationaccording to an embodiment of the present invention.

FIG. 4 is a block diagram illustrating a configuration of an accesspoint according to an embodiment of the present invention.

FIG. 5 is a view illustrating a process that a station sets an accesspoint and a link according to an embodiment of the present invention.

FIG. 6 shows that an access point according to an embodiment of thepresent invention generates an orthogonal code set for a random access.

FIG. 7 shows that a wireless communication terminal according to anembodiment of the present invention decodes a signal based on anorthogonal code set for a random access.

FIG. 8 shows that a wireless communication terminal according to anembodiment of the present invention decodes a plurality of signals basedon an identical orthogonal code set for the random access.

FIG. 9 shows a structure of an access signal according to an embodimentof the present invention.

FIG. 10 shows a structure of the access signal according to anotherembodiment of the present invention.

FIG. 11 shows a frame including information on the orthogonal code setfor the random access according to an embodiment of the presentinvention.

FIG. 12 shows that a wireless communication terminal according to anembodiment of the present invention performs the random access on thebasis of a frame including information on the orthogonal code set forthe random access.

FIG. 13 shows that a plurality of stations according to an embodiment ofthe present invention transmit data to an access point through therandom access.

FIG. 14 shows that the plurality of stations according to an embodimentof the present invention transmit data to the access point when theplurality of stations use an overlapping orthogonal code set.

FIG. 15 shows that the plurality of stations according to an embodimentof the present invention transmit data to the access point on the basisof a trigger frame through which the plurality of stations triggeruplink transmission.

FIG. 16 shows a basic service set including the plurality of stationsand the access point according to an embodiment of the presentinvention.

FIG. 17 shows that the plurality of stations according to an embodimentof the present invention transmit data to the access point, when idlechannels sensed by the plurality of stations are different from thosesensed by the access point.

FIG. 18 shows that the plurality of stations according to an embodimentof the present invention transmit data to the access point inconsideration of a station that does not support the embodiment of thepresent invention.

FIG. 19 shows operations of the plurality of stations in considerationof a case where a channel allocation processing time by the access pointaccording to an embodiment of the present invention is delayed.

FIG. 20 is a ladder diagram showing an operation in which the secondwireless communication terminal according to an embodiment of thepresent invention transmits data to the first wireless communicationterminal.

MODE FOR CARRYING OUT THE INVENTION

Preferred embodiments of the present invention will be described belowin more detail with reference to the accompanying drawings. The presentinvention may, however, be embodied in different forms and should not beconstructed as limited to the embodiments set forth herein. Parts notrelating to description are omitted in the drawings in order to clearlydescribe the present invention and like reference numerals refer to likeelements throughout.

Furthermore, when it is described that one comprises (or includes orhas) some elements, it should be understood that it may comprise (orinclude or has) only those elements, or it may comprise (or include orhave) other elements as well as those elements if there is no specificlimitation.

This application claims priority to and the benefit of Korean PatentApplication Nos. 10-2014-0114611 and Nos. 10-2014-0114612 filed in theKorean Intellectual Property Office and the embodiments and mentioneditems described in the respective applications are included in theDetailed Description of the present application.

FIG. 1 is a diagram illustrating a wireless LAN system according to anembodiment of the present invention. The wireless LAN system includesone or more basic service sets (BSS) and the BSS represents a set ofapparatuses which are successfully synchronized with each other tocommunicate with each other. In general, the BSS may be classified intoan infrastructure BSS and an independent BSS (IBSS) and FIG. 1illustrates the infrastructure BSS between them.

As illustrated in FIG. 1 , the infrastructure BSS (BSS1 and BSS2)includes one or more stations STA1, STA2, STA3, STA4, and STA5, accesspoints PCP/AP-1 and PCP/AP-2 which are stations providing a distributionservice, and a distribution system (DS) connecting the multiple accesspoints PCP/AP-1 and PCP/AP-2.

The station (STA) is a predetermined device including medium accesscontrol (MAC) following a regulation of an IEEE 802.11 standard and aphysical layer interface for a radio medium, and includes both anon-access point (non-AP) station and an access point (AP) in a broadsense. Further, in the present specification, a term ‘terminal’ may beused to refer to a concept including a wireless LAN communication devicesuch as non-AP STA, or an AP, or both terms. A station for wirelesscommunication includes a processor and a transceiver and according tothe embodiment, may further include a user interface unit and a displayunit. The processor may generate a frame to be transmitted through awireless network or process a frame received through the wirelessnetwork and besides, perform various processing for controlling thestation. In addition, the transceiver is functionally connected with theprocessor and transmits and receives frames through the wireless networkfor the station.

The access point (AP) is an entity that provides access to thedistribution system (DS) via wireless medium for the station associatedtherewith. In the infrastructure BSS, communication among non-APstations is, in principle, performed via the AP, but when a direct linkis configured, direct communication is enabled even among the non-APstations. Meanwhile, in the present invention, the AP is used as aconcept including a personal BSS coordination point (PCP) and mayinclude concepts including a centralized controller, a base station(BS), a node-B, a base transceiver system (BTS), and a site controllerin a broad sense.

A plurality of infrastructure BSSs may be connected with each otherthrough the distribution system (DS). In this case, a plurality of BSSsconnected through the distribution system is referred to as an extendedservice set (ESS).

FIG. 2 illustrates an independent BSS which is a wireless LAN systemaccording to another embodiment of the present invention. In theembodiment of FIG. 2 , duplicative description of parts, which are thesame as or correspond to the embodiment of FIG. 1 , will be omitted.

Since a BSS3 illustrated in FIG. 2 is the independent BSS and does notinclude the AP, all stations STA6 and STA7 are not connected with theAP. The independent BSS is not permitted to access the distributionsystem and forms a self-contained network. In the independent BSS, therespective stations STA6 and STA7 may be directly connected with eachother.

FIG. 3 is a block diagram illustrating a configuration of a station 100according to an embodiment of the present invention.

As illustrated in FIG. 3 , the station 100 according to the embodimentof the present invention may include a processor 110, a transceiver 120,a user interface unit 140, a display unit 150, and a memory 160.

First, the transceiver 120 transmits and receives a radio signal such asa wireless LAN packet, or the like and may be embedded in the station100 or provided as an exterior. According to the embodiment, thetransceiver 120 may include at least one transmit/receive module usingdifferent frequency bands. For example, the transceiver 120 may includetransmit/receive modules having different frequency bands such as 2.4GHz, 5 GHz, and 60 GHz. According to an embodiment, the station 100 mayinclude a transmit/receive module using a frequency band of 6 GHz ormore and a transmit/receive module using a frequency band of 6 GHz orless. The respective transmit/receive modules may perform wirelesscommunication with the AP or an external station according to a wirelessLAN standard of a frequency band supported by the correspondingtransmit/receive module. The transceiver 120 may operate only onetransmit/receive module at a time or simultaneously operate multipletransmit/receive modules together according to the performance andrequirements of the station 100. When the station 100 includes aplurality of transmit/receive modules, each transmit/receive module maybe implemented by independent elements or a plurality of modules may beintegrated into one chip.

Next, the user interface unit 140 includes various types of input/outputmeans provided in the station 100. That is, the user interface unit 140may receive a user input by using various input means and the processor110 may control the station 100 based on the received user input.Further, the user interface unit 140 may perform output based on acommand of the processor 110 by using various output means.

Next, the display unit 150 outputs an image on a display screen. Thedisplay unit 150 may output various display objects such as contentsexecuted by the processor 110 or a user interface based on a controlcommand of the processor 110, and the like. Further, the memory 160stores a control program used in the station 100 and various resultingdata. The control program may include an access program required for thestation 100 to access the AP or the external station.

The processor 110 of the present invention may execute various commandsor programs and process data in the station 100. Further, the processor110 may control the respective units of the station 100 and control datatransmission/reception among the units. According to the embodiment ofthe present invention, the processor 110 may execute the program foraccessing the AP stored in the memory 160 and receive a communicationconfiguration message transmitted by the AP. Further, the processor 110may read information on a priority condition of the station 100 includedin the communication configuration message and request the access to theAP based on the information on the priority condition of the station100. The processor 110 of the present invention may represent a maincontrol unit of the station 100 and according to the embodiment, theprocessor 110 may represent a control unit for individually controllingsome component of the station 100, for example, the transceiver 120, andthe like. The processor 110 controls various operations of radio signaltransmission/reception of the station 100 according to the embodiment ofthe present invention. A detailed embodiment thereof will be describedbelow.

The station 100 illustrated in FIG. 3 is a block diagram according to anembodiment of the present invention, where separate blocks areillustrated as logically distinguished elements of the device.Accordingly, the elements of the device may be mounted in a single chipor multiple chips depending on design of the device. For example, theprocessor 110 and the transceiver 120 may be implemented while beingintegrated into a single chip or implemented as a separate chip.Further, in the embodiment of the present invention, some components ofthe station 100, for example, the user interface unit 140 and thedisplay unit 150 may be optionally provided in the station 100.

FIG. 4 is a block diagram illustrating a configuration of an AP 200according to an embodiment of the present invention.

As illustrated in FIG. 4 , the AP 200 according to the embodiment of thepresent invention may include a processor 210, a transceiver 220, and amemory 260. In FIG. 4 , among the components of the AP 200, duplicativedescription of parts which are the same as or correspond to thecomponents of the station 100 of FIG. 2 will be omitted.

Referring to FIG. 4 , the AP 200 according to the present inventionincludes the transceiver 220 for operating the BSS in at least onefrequency band. As described in the embodiment of FIG. 3 , thetransceiver 220 of the AP 200 may also include a plurality oftransmit/receive modules using different frequency bands. That is, theAP 200 according to the embodiment of the present invention may includetwo or more transmit/receive modules among different frequency bands,for example, 2.4 GHz, 5 GHz, and 60 GHz together. Preferably, the AP 200may include a transmit/receive module using a frequency band of 6 GHz ormore and a transmit/receive module using a frequency band of 6 GHz orless. The respective transmit/receive modules may perform wirelesscommunication with the station according to a wireless LAN standard of afrequency band supported by the corresponding transmit/receive module.The transceiver 220 may operate only one transmit/receive module at atime or simultaneously operate multiple transmit/receive modulestogether according to the performance and requirements of the AP 200.

Next, the memory 260 stores a control program used in the AP 200 andvarious resulting data. The control program may include an accessprogram for managing the access of the station. Further, the processor210 may control the respective units of the AP 200 and control datatransmission/reception among the units. According to the embodiment ofthe present invention, the processor 210 may execute the program foraccessing the station stored in the memory 260 and transmitcommunication configuration messages for one or more stations. In thiscase, the communication configuration messages may include informationabout access priority conditions of the respective stations. Further,the processor 210 performs an access configuration according to anaccess request of the station. The processor 210 controls variousoperations such as radio signal transmission/reception of the AP 200according to the embodiment of the present invention. A detailedembodiment thereof will be described below.

FIG. 5 is a diagram schematically illustrating a process in which a STAsets a link with an AP.

Referring to FIG. 5 , the link between the STA 100 and the AP 200 is setthrough three steps of scanning, authentication, and association in abroad way. First, the scanning step is a step in which the STA 100obtains access information of BSS operated by the AP 200. A method forperforming the scanning includes a passive scanning method in which theAP 200 obtains information by using a beacon message (S101) which isperiodically transmitted and an active scanning method in which the STA100 transmits a probe request to the AP (S103) and obtains accessinformation by receiving a probe response from the AP (S105).

The STA 100 that successfully receives wireless access information inthe scanning step performs the authentication step by transmitting anauthentication request (S107 a) and receiving an authentication responsefrom the AP 200 (S107 b). After the authentication step is performed,the STA 100 performs the association step by transmitting an associationrequest (S109 a) and receiving an association response from the AP 200(S109 b).

Meanwhile, an 802.1X based authentication step (S111) and an IP addressobtaining step (S113) through DHCP may be additionally performed. InFIG. 5 , the authentication server 300 is a server that processes 802.1Xbased authentication with the STA 100 and may be present in physicalassociation with the AP 200 or present as a separate server.

When data is transmitted using an orthogonal frequency divisionmodulation or multi-input multi-output (MIMO) manner, any one wirelesscommunication terminal may simultaneously transmit data to a pluralityof wireless communication terminals. In addition, the any one wirelesscommunication terminal may simultaneously receive data from theplurality of wireless communication terminals. To this end, the any onewireless communication terminal may transmit a method capable ofaccessing itself to the plurality of wireless communication terminals.The plurality of wireless communication terminals may access the any onewireless communication terminal on the basis of the access method havingbeen transmitted by the any one wireless communication terminal. Anembodiment of the present invention in which the plurality of wirelesscommunication terminals access the any one wireless communicationterminal and on the basis of such an access and the plurality ofwireless communication terminals transmit data to the any one wirelesscommunication terminal will be described through drawings after FIG. 5and descriptions thereabout.

For convenience of description, the any one wireless communicationcommunicating with the plurality of wireless communication terminals isreferred to as a first wireless communication terminal, and theplurality of wireless communication terminals simultaneouslycommunicating with the first wireless communication terminal arereferred to as second wireless communication terminals. In addition, thefirst wireless communication terminal may be referred to as a basewireless communication terminal. Furthermore, the first wirelesscommunication terminal may be a wireless communication terminalperforming allocation and scheduling on a communication medium resourcein communications with the plurality of wireless communicationterminals. In detail, the first wireless communication terminal mayperform a cell coordinator role. At this point, the first wirelesscommunication terminals may be an access point 200. In addition, thesecond wireless communication terminal may be a station 100 associatedwith the access point 200. In a detailed embodiment, the first wirelesscommunication terminal may be a wireless communication terminalperforming allocation and scheduling on a communication medium resourcein an independent network that is not connected to an externaldistribution service such as an ad-hoc network. Furthermore, the firstwireless communication terminal may be at least any one of a basestation, an eNB, and a transmission point (TP).

FIG. 6 shows that an access point according to an embodiment of thepresent invention generates an orthogonal code set for a random access.

The first wireless communication terminal may designate a plurality ofaccess manners through which the plurality of second wirelesscommunication terminals may access using a certain communication manner.The second wireless communication terminal may access the first wirelesscommunication terminal through any one of the designated plurality ofaccess manners. In detail, the first wireless communication terminal maydesignate an orthogonal code set accessible by the plurality of secondwireless communication terminals. Accordingly, the second wirelesscommunication terminals may access the first wireless communicationterminal using any one orthogonal code in the orthogonal code set. Indetailed embodiment, a base sequence that is different from an adjacentBSS is allocated to a BSS. For example, a plurality of base sequencesmay be respectively allocated to a plurality of BSSes. The first andsecond wireless communication terminals in each of the plurality ofBSSes generate a plurality of orthogonal codes included in theorthogonal code set on the basis of the allocated base sequence. Indetail, the first and second wireless communication terminals generate aplurality of orthogonal codes included in the orthogonal code set bycyclic-shifting the allocated base sequence. In detail, the first andsecond wireless communication terminals may receive an index indicatingthe base sequence. At this point, the first and second wirelesscommunication terminals may acquire the base sequence according to theindex indicating the base sequence. Thereafter, the first and secondwireless communication terminals may generate the plurality oforthogonal codes included in the code set using the acquired basesequence according to the pre-designated length of the base sequence anda cyclic-shifting size. When the BSS uses 8 channels of a 20 MHz unit,the number of the base sequence lengths may be equal to or greater than8. For stable zero auto-correlation characteristics, the base sequencemay be lengthened. Through this, the first and second wirelesscommunication terminals may minimize base sequence interference betweenadjacent BSSes. In a detailed embodiment, the first and second wirelesscommunication terminals may generate a base sequence by using aZadoff-Chu sequence satisfying constant amplitude zero auto correlation(CAZAC) characteristics.

The second wireless communication terminal may randomly select to useany one of a plurality of access manners designated by the firstwireless communication terminal. In detail, the second wirelesscommunication terminal may randomly select any one of the generatedorthogonal code sets to use as a multiple-access code. In anotherdetailed embodiment, the second wireless communication terminal may usea fixed orthogonal code. At this point, the fixed orthogonal code may beobtained by modulo-operating an identifier of the second wirelesscommunication terminal with the size of the orthogonal code set. At thispoint, the identifier of the second wireless communication terminal maybe an AID for identifying an association of the first and secondwireless communication terminals. The plurality of second wirelesscommunication terminals maintain orthogonality between orthogonal codes,even if accessing through different orthogonal codes. Accordingly, thefirst wireless communication terminal may know, through anautocorrelation operation for the base sequence, which code the secondwireless communication terminal uses in an access. In particular, in acase where the CAZAC sequence is used, when the base sequence lengthbecomes longer, the number of codes included in the code set increases.Accordingly, a probability that codes overlap between wirelesscommunication terminals becomes reduced. A description about that thefirst wireless communication terminal decodes a received signal toacquire a code will be provided in relation to FIGS. 7 and 8 .

FIG. 7 shows that a wireless communication terminal according to anembodiment of the present invention decodes a signal based on anorthogonal code set for a random access.

When the plurality of second wireless communication terminalssimultaneously access the first wireless communication terminal, thefirst wireless communication terminal receives signals in a type thatrespective signals from the plurality of second wireless communicationterminals are added. At this point, the plurality of first wirelesscommunication terminals perform autocorrelation operations to obtainpatterns of codes respectively corresponding to the plurality ofsignals. Through this, the first wireless communication terminal mayidentify the second wireless communication terminals having transmittedthe respective signals. In addition, the first wireless communicationterminal may obtain information included in each of the signals

In the embodiment of FIG. 7 , a first station STA1, a second stationSTA2, and a fourth station STA4 access the first wireless communicationterminal through a secondary channel CH2. At this point, the firststation STA1, the second station STA2, and the fourth station STA4access an access point using different orthogonal codes 701. At thispoint, the first station STA1, the second station STA2, and the fourthstation STA4 may use the orthogonal codes respectively pre-designatedthereto. In another detailed embodiment, the first station STA1, thesecond station STA2, and the fourth station STA4 may randomly select anyone orthogonal code from the code set including the plurality oforthogonal codes. Accordingly, the access point receives a signal 702 inwhich a signal from the first station STA1, a signal from the secondstation STA2 and a signal from the fourth station STA4 are added. Atthis point, respective orthogonal codes used by the first station STA1,the second station STA2 and the fourth station STA4 have different shiftpositions 703 of the auto-correlation. Accordingly, the access pointperforms the auto-correlation operation on the received signal andacquires orthogonal code patterns 704 respectively corresponding to thefirst station STA1, the second station STA2 and the fourth station STA4having different shift positions from each other. Accordingly, theaccess point may identify a station having transmitted the signal andacquire information included in the signal.

FIG. 8 shows that a wireless communication terminal according to anembodiment of the present invention decodes a plurality of signals basedon an identical orthogonal code set for the random access.

When a random access through the orthogonal code is allowed, even a casewhere the plurality of second wireless communication terminals accessthrough an identical orthogonal code, the plurality of second wirelesscommunication terminals may be identified. In detail, the first wirelesscommunication terminal performs auto-correlation on a received signal toacquire an orthogonal code pattern. At this point, even when theplurality of second wireless communication terminals use an identicalorthogonal code, when distances between the first wireless communicationterminal and the plurality of second wireless communication terminalsare different, peak values of orthogonal code patterns of the pluralityof second wireless communication terminals may show identifiably largedifferences. Accordingly, even when the plurality of second wirelesscommunication terminals select the identical orthogonal code, the firstwireless communication terminal may identify signals having beenrespectively transmitted from the plurality of second wirelesscommunication terminals. However, when respective distances between thefirst wireless communication terminal and the plurality of secondwireless communication terminals are similar to each other and then thepeak values of the orthogonal code patterns are not identifiable, thefirst wireless communication terminal may not identify respectivesignals having been received from the plurality of second wirelesscommunication terminals. At this point, the first wireless communicationterminal may treat the signals having been received from the pluralityof second wireless communication terminals as being collided.

In the embodiment of FIG. 8 , a first station and a second stationtransmit signals using an identical orthogonal code to an access point.The access point performs an auto-correlation operation on receivedsignals to acquire an orthogonal code 801 used by the first and secondstations. At this point, since a peak value of the orthogonal codepattern from the first station differs from a peak value of theorthogonal code pattern from the second station, the access point mayidentify the orthogonal code patterns of the first and second stations.

In this way, when the second wireless communication terminal performs amultiple access using the orthogonal code value, even when the pluralityof second wireless communication terminals use an identical orthogonalcode, there is a possibility that orthogonal code patterns of thesignals having been received from the plurality of second wirelesscommunication terminals are identified. Unlike this, when the secondwireless communication terminal performs a multiple access in anorthogonal frequency divisional multiple access (OFDMA) scheme and theplurality of second wireless communication terminals use an identicalfrequency band, the first wireless communication terminal may notreceive a signal transmitted from the second wireless communicationterminal. Accordingly, in view of signal identification, the multipleaccess through the orthogonal code may be more efficient than themultiple access through the OFDMA. In particular, like a random multipleaccess, when there is a concern that the plurality of second wirelesscommunication terminals access the first wireless communication terminalin an identical manner, the multiple access through the orthogonal codemay be more efficient than the multiple access through the OFDMA.

When the second wireless communication terminal accesses the firstwireless communication terminal by using the orthogonal code, a detailedsignal format used by the second wireless communication terminal will bedescribed in relation to FIGS. 9 and 10 .

FIG. 9 shows a structure of an access signal according to an embodimentof the present invention.

An access signal transmitted by the second wireless communicationterminal to the first wireless communication terminal may include a codepart 901 including information on an orthogonal code and a data part 902including information other than the orthogonal code.

All subcarriers in a frequency band of the code part 901 may carry theorthogonal code selected by the second wireless communication terminal.In detail, the second wireless communication terminal may transmit, tothe first wireless communication terminal, the code selected by thesecond wireless communication terminal through the all subcarriers inthe code part 901. When a frequency bandwidth of the code part 901 is 20MHz and the second wireless communication terminal performscommunication using 64-point Fast Fourier transform (FFT), the secondwireless communication terminal may transmit the code selected by thesecond wireless communication terminal using 52 subcarriers in the codepart 901. Through this, the code part 901 performs a role of a trainingsequence enabling a channel state of each terminal to be known, whileperforming a role of a preamble. In addition, in a detailed embodiment,the duration of the code part may be pre-designated.

In addition, a specific subcarrier in the data part 902 may transmitinformation other than the orthogonal code. At this point, the specificsubcarrier may be a subcarrier allocated to the orthogonal codetransmitted by the code part 901. In this case, the first wirelesscommunication terminal may acquire the orthogonal code from the codepart 901 and acquire information included in the data part 902 from thesubcarrier and frequency band allocated to the corresponding orthogonalcode.

In detail, when the second wireless communication terminal directlytransmits data through a random access, the data part 902 may includedata to be transmitted by the second wireless communication terminal. Inanother detailed embodiment, when the second wireless communicationterminal transmits required information for being allocated with achannel and then transmits data, the data part 902 may include therequired information for being allocated with the channel. In detail,the data part 902 may include an identifier for identifying the secondwireless communication terminal. At this point, the identifier may be anassociation ID (AID) for identifying association with the first wirelesscommunication terminal. In a detailed embodiment, the identifier may bea partial AID. In addition, the data part 902 may include information ona buffer status. In detail, the data part 902 may include data sizeinformation indicating the size of data to be transmitted to the firstwireless communication terminal by the second wireless communicationterminal. In addition, the data part 902 may include channel accessinformation indicating a channel to be used for an access by the secondwireless communication terminal.

In the embodiment of FIG. 9 , the code part 901 transmits a fifth codethrough 52 subcarriers. In addition, the data part 902 transmits,through the subcarriers allocated to the fifth code, FCS valuesindicating an AID, the size of data to be transmitted from the secondwireless communication terminal to the first wireless communicationterminal, channel information with which the second wirelesscommunication terminal seeks to be allocated, and whether to include anerror of the data.

As described above, each of the plurality of second wirelesscommunication terminals may use a fixed code allocated thereto. In thiscase, the first wireless communication terminal acquires the orthogonalcode to identify which of the second wireless communication terminalstransmits the corresponding signal. Accordingly, in this case, astructure of an access signal transmitted from the second wirelesscommunication terminal to the first wireless communication terminalbecomes simpler. A description thereabout will be provided in relationto FIG. 10 .

FIG. 10 shows a structure of the access signal according to anotherembodiment of the present invention.

The access signal transmitted from the second wireless communicationterminal to the first wireless communication terminal may includeinformation indicating the size of data to be transmitted from thesecond wireless communication terminal to the first wirelesscommunication terminal. In addition, the access signal may be a signalin which the orthogonal code used by the first wireless communicationterminal is patterned by a symbol unit. In detail, whether each of aplurality of OFDM symbols included in the access signal includes anorthogonal code may indicate the size of data to be transmitted from thesecond wireless communication terminal to the first wirelesscommunication terminal. For example, for each OFDM symbol included inthe access signal, whether the corresponding symbol includes theorthogonal code may indicate each binary bit value indicating the sizeof data to be transmitted to the first wireless communication terminal.At this point, when the OFDM symbol included in the access signalincludes the orthogonal code, it may be indicated that a binary bitvalue corresponding to an order in which the OFDM symbol is positionedis 1. In addition, when the OFDM symbol included in the access signalincludes a Null value, it may be indicated that a binary bit valuecorresponding to an order in which the OFDM symbol is positioned is 0.

Furthermore, the frequency bandwidth is 20 MHz, and when the secondwireless communication terminal uses 64-point FFT, the second wirelesscommunication terminal may transmit the access signal using 52subcarriers.

In the embodiment of FIG. 10 , the second wireless communicationterminal transmits the access signal to the first wireless communicationterminal using a second code. At this point, the size of data that thesecond wireless communication terminal seeks to transmit to the firstwireless communication terminal is 100 (01100100b). Accordingly, thesecond wireless communication terminal inserts the second code tosecond, third, and sixth OFDM symbols of the access signal to betransmitted to the first wireless communication terminal and inserts aNull value to the remaining OFDM symbols.

In order to allow the plurality of second wireless communicationterminals to simultaneously attempt an access, the first wirelesscommunication terminal assigns a time to attempt the access to theplurality of second wireless communication terminals and signals thetime to the plurality of second wireless communication terminals. Atthis point, the second wireless communication terminals may transmit, atthe assigned time, required information for being allocated with achannel or directly transmit data to the first wireless communicationterminal. In relation to FIGS. 11 and 12 , an embodiment in which thefirst wireless communication terminal signals an uplink access time tothe second wireless communication terminals will be described.

FIG. 11 shows a frame including information on the orthogonal code setfor the random access according to an embodiment of the presentinvention.

The first wireless communication terminal may transmit, to the secondwireless communication terminal, a frame including information requiredfor an access to the first wireless communication terminal. In detail,the first wireless communication terminal may transmit a frame includingat least any one of information indicating an access time thereto andinformation on an access manner thereto. At this point, the informationindicating the access time thereto may be an access period. For example,the first wireless communication terminal may transmit a frame includinginformation indicating the number of transmission times to the secondwireless communication terminal. At this point, the second wirelesscommunication terminal may attempt an access to the first wirelesscommunication terminal in a period obtained by equally dividing a frametransmission period by the number of transmission times. In addition,the information on the access manner may be information on theorthogonal code used for the access. In detail, the information on theorthogonal code may be information indicating a base sequence capable ofgenerating the orthogonal code. At this point, the informationindicating the base sequence may be a sequence index.

In a detailed embodiment, the first wireless communication terminal mayinclude at least any one of information indicating an uplink access timeand information on an uplink access manner in a beacon frame, andtransmit the beacon frame. In detail, as in the embodiment of FIG. 9 ,the beacon frame may include a UL-OFDMA count field indicating an uplinktransmission times in a transmission period of the beacon frame. Indetail, the second wireless communication terminal may acquire a valueobtained by dividing the transmission period of the beacon frame by theUL-OFDMA count field value. The second wireless communication terminalmay access the first wireless communication terminal in an access timeperiod of the acquired value. In addition, the beacon frame may includea code index field indicating a code capable of generating a CAZAC basesequence. In detail, the beacon frame may include, as informationelements, the UL-OFDMA count field and the code index field. At thispoint, a value of an element ID field indicating an element identifiermay be a reserved value in existing 802.11 standards.

FIG. 12 shows that a wireless communication terminal according to anembodiment of the present invention performs the random access on thebasis of a frame including information on the orthogonal code set forthe random access.

The second wireless communication terminal may periodically access thefirst wireless communication terminal. At this point, as describedabove, the second wireless communication terminal may periodicallyaccess the first wireless communication terminal according to an accessperiod designated by the first wireless communication terminal. In adetailed embodiment, when a channel, which will be used by the secondwireless communication terminal in order to access the first wirelesscommunication terminal at the designated time, is used by anotherwireless communication terminal, the second wireless communicationterminal may wait until the corresponding channel becomes an idle state.Thereafter, when the corresponding channel becomes the idle state, thesecond wireless communication terminal may attempt an access to thefirst wireless communication terminal.

At this point, the second wireless communication terminals may accessthe first wireless communication terminal to transmit requiredinformation for being allocated with a channel or directly transmit datathereto. The required information for being allocated with the channelmay include information on a buffer state of the second wirelesscommunication terminal. At this point, the information on the bufferstate may include at least any one of whether there is data to becurrently transmitted and the size of data to be transmitted.

In the embodiment of FIG. 12 , the first wireless communication terminaltransmits a beacon frame.

The second wireless communication terminal acquires information on anaccess period from the beacon frame.

The second wireless communication terminal attempts an access at everythree access times 1201 according to the information on the transmissionperiod. However, like a second access time, when a channel to which anaccess is attempted is not in an idle state but in a busy state, thesecond wireless communication terminal waits until the channel becomesthe idle state. When the channel becomes the idle state, the secondwireless communication terminal accesses 1202 the first wirelesscommunication terminal.

As described above, the second wireless communication terminal maytransmit the required information for being allocated with the channelbefore transmitting data to the first wireless communication terminal.At this point, the first wireless communication terminal may allocate achannel to the second wireless communication terminal on the basis ofthe required information for being allocated with the channel. Forexample, the first wireless communication terminal may allocaterespective channels to be used by the plurality of second wirelessterminals to the plurality of second wireless terminals in considerationof respective buffer states of the plurality of second wirelesscommunication terminals. At this point, since the plurality of secondwireless communication terminals use channels allocated thereto,collisions may be prevented due to transmissions by the plurality ofsecond wireless communication terminals. Accordingly, the secondwireless communication terminals may transmit, to the first wirelesscommunication terminal, data more stably and efficiently than a directtransmission case. In relation to FIGS. 12 to 19 , it will be provided adetailed description about data transmission by the second wirelesscommunication terminal to the first wireless communication terminal,after the second wireless communication terminal transmits the secondwireless communication terminal's buffer state.

FIG. 13 shows that a plurality of stations according to an embodiment ofthe present invention transmit data to an access point through therandom access.

The second wireless communication terminal transmits requiredinformation for being allocated with the second wireless communicationterminal's channel to the first wireless communication terminal. Indetail, the second wireless communication terminal may transmit therequired information for being allocated with the second wirelesscommunication terminal's channel using any one orthogonal code in a codeset including a plurality of orthogonal codes. At this point, asdescribed above, the orthogonal code set may be generated based on theinformation transmitted from the first wireless communication terminal.For example, the second wireless communication terminal may receive,from the first wireless communication terminal, a frame includinginformation on the orthogonal code set. At this point, the secondwireless communication terminal may acquire an orthogonal code on thebasis of the information on the orthogonal code set. In another detailedembodiment, the second wireless communication terminal may transmit itsown buffer state using the orthogonal code allocated in advance to thesecond wireless communication terminal. At this point, the firstwireless communication terminal may allocate the orthogonal codecorresponding to the second wireless communication terminal as anassociation identifier for identifying association of the secondwireless communication terminal with the first wireless communicationterminal. At this point, the association identifier may be an AID. Inthis case, the second wireless communication terminal may transmit therequired information for being allocated with the channel using theassociation identifier as the orthogonal code.

In addition, the second wireless communication terminal may transmit therequired information for being allocated with the channel beforetransmitting data to the first wireless communication terminal at thedesignated time. At this point, the determined time may be a timedesignated by the first wireless communication terminal as described inrelation to FIGS. 11 and 12 . In a detailed embodiment, the secondwireless communication terminal may acquire the designated time on thebasis of a beacon frame transmitted by the first wireless communicationterminal.

In addition, the second wireless communication terminal may transmit therequired information for being allocated with the channel to the firstwireless communication terminal, after a predetermined time passes froma transmission time of a frame that has been transmitted before. At thispoint, the predetermined time may be a point inter-frame space (PIFS)defined in 802.11 standards.

The first wireless communication terminal may allocate a channel to eachof the plurality of second wireless communication terminals on the basisof the received required information for being allocated with thechannel.

At this point, as described above, the required information for beingallocated with the channel may include information indicating the sizeof data to be transmitted by the second wireless communication terminal.In addition, the required information for being allocated with thechannel may include an identifier for identifying the second wirelesscommunication terminal. At this point, the identifier for identifyingthe second wireless communication terminal may be an AID or a partialAID for identifying an association with the first wireless communicationterminal. In addition, the required information for being allocated withthe channel may include channel access map information indicating achannel with which the second wireless communication terminal desires tobe allocated. At this point, the channel access map information mayinclude information on an idle channel sensed by the second wirelesscommunication terminal. A description regarding this will be providedlater in relation to FIGS. 16 and 17 .

The first wireless communication terminal transmits a frame indicating achannel allocated to the second wireless communication terminal. Indetail, the first wireless communication terminal may transmit the frameindicating the channel allocated to the second wireless communicationterminal through the channel allocated to wireless communicationterminal. At this point, the frame indicating the channel allocated tothe second wireless communication terminal may include informationindicating a time available for data transmission by the second wirelesscommunication terminal. At this point, the time available for datatransmission may be a time commonly applied to the plurality of secondwireless communication terminals. Accordingly, the time available forthe data transmission may be determined based on the longest time amongrequired times for data transmission by the plurality of second wirelesscommunication terminals. At this point, the time available for datatransmission may be transmitted as a duration field value of a frameindicating the channel allocated to the second wireless communicationterminal. Accordingly, the duration field value of the frame indicatingthe channel allocated to the second wireless communication terminal maybe designated based on a required transmission time of the largest dataamong pieces of transmission data by the plurality of second wirelesscommunication terminals. In addition, the frame indicating the channelallocated to the second wireless communication terminal may be a CTSframe.

The second wireless communication terminal acquires information on achannel allocated thereto on the basis of the frame indicating thechannel allocated to the second wireless communication terminal. Whenthe frame indicating the channel allocated to the second wirelesscommunication terminal is the CTS frame, the second wirelesscommunication terminal determines, as a channel allocated thereto, achannel through which a CTS frame has been transmitted, the CTS framehaving a receiver address (RA) as an identifier for identifying thesecond wireless communication terminal. At this point, the identifierfor identifying the second wireless communication terminal may be amedia access control (MAC) address corresponding to an AID of the secondwireless communication terminal.

The second wireless communication terminal transmits data to the firstwireless communication terminal through the channel allocated to thecommunication terminal. At this point, when a time is left fortransmitting data after transmitting the second wireless communicationterminal's data, the second wireless communication terminal may transmitdummy data. At this point, the dummy data indicates meaningless datadistinguished from meaningful data transmitted through a data frame. Indetail, the dummy data may have a pattern in which a specific value like“0” is continued. In detail, the dummy data may be referred to as abusytone. In a detailed embodiment, the second wireless communicationterminal may transmit data, and transmit the dummy data during a timewhen data may be transmitted after the data frame is transmitted. Afterthe data frame transmission may indicate after an FCS field of the dataframe is transmitted. In addition, the data frame is a frametransmitting data distinguished from a control frame. In detail, thedata frame may include meaningful data distinguished from the dummydata. At this point, as described above, the second wirelesscommunication terminal may acquire, from a frame indicating the channelallocated to the second wireless communication terminal, information ona time when the data may be transmitted. In detail, the second wirelesscommunication terminal may acquire, from a duration field of a frameindicating the channel allocated to the second wireless communicationterminal, the time when the data may be transmitted.

Through such an operation of the second wireless communication terminal,another wireless communication terminal may be prevented from using thecorresponding channel. In addition, when the second wirelesscommunication terminal transmits the dummy data after transmitting thedata frame, the first wireless communication terminal does not requireprocessing data to be transmitted through the corresponding channelduring transmission of the dummy data. Accordingly, through such anoperation, a processing burden on the first wireless communicationterminal may be reduced.

The first wireless communication terminal transmits an ACK frame to eachof the plurality of second wireless communication terminals that hastransmitted data through the channel allocated thereto.

In the embodiment of FIG. 13 , a first station STA1, a second stationSTA2, a third station STA3, and a fourth station STA4 respectivelytransmit required information for channel allocation to an access pointAP using different orthogonal codes (operation S1301).

The access point AP performs autocorrelation on the received signal toacquire required information for channel allocation from respectivesignals transmitted from the first station STA1, the second stationSTA2, the third station STA3, and the fourth station STA4. At thispoint, since the first station STA1, the second station STA2, the thirdstation STA3, and the fourth station STA4 use different orthogonalcodes, the access point may distinguish the signals transmitted from thefirst station STA1, the second station STA2, the third station STA3, andthe fourth station STA4.

The access point AP allocates channels to the first station STA1, thesecond station STA2, the third station STA3, and the fourth station STA4on the basis of the required information for channel allocation. At thispoint, the access point AP senses idle channels and allocates the idlechannels to the first station STA1, the second station STA2, and thethird station STA3. In detail, the access point AP allocates a primarychannel Primary to the first station STA1, a first secondary channelSecondary 1 to the second station STA2, a sixth secondary channelSecondary 6 to the third station, and a second secondary channelSecondary 2 to the fourth station.

The access point AP transmits a CTS frame to the first station STA1, thesecond station STA2, the third station STA3, and the fourth station STA4through respective channels allocated thereto (operation S1302).

The first station STA1, the second station STA2, the third station STA3,and the fourth station STA4 transmit data through the respectivechannels allocated thereto (operation S1303). At this point, the secondstation STA2, the third station STA3, and the fourth station STA4transmit dummy data until transmission by the first station STA1 will beterminated, even after data transmissions of their own were terminated.At this point, detailed transmission operations of the second stationSTA2, the third station STA3, and the fourth station STA4 may be thesame as described above.

The access point AP receives data from each of the first station STA1,the second station STA2, the third station STA3, and the fourth stationSTA4 and transmits an ACK frame to each of the first station STA 1, thesecond station STA2, the third station STA3, and the fourth stationSTA4.

FIG. 14 shows that the plurality of stations according to an embodimentof the present invention transmit data to the access point when theplurality of stations use an overlapping orthogonal code set.

As described above, when the plurality of second wireless communicationterminals transmit signals using an identical orthogonal code, in somecases, the first wireless communication terminal may not decode thesignals having been transmitted by the plurality of second wirelesscommunication terminals. In such a case, the first communicationterminal allocates a channel only for a second communication terminalhaving transmitted a decodable signal and transmits a frame indicating achannel allocated to the second wireless communication terminal havingtransmitted the decodable signal.

In the embodiment of FIG. 14 , the first station STA1 and the fourthstation STA4 transmit required information for channel allocation to anaccess point AP by using different orthogonal codes (operation S1401).However, the second station STA2 and the third station STA3 transmitrequired information for channel allocation to the access point AP byusing an identical orthogonal code.

The access point (AP) performs autocorrelation on the received signal toacquire required information for channel allocation from respectivesignals transmitted from the first station STA1 and the fourth stationSTA4. At this point, since the first station STA1 and the fourth stationSTA4 uses different orthogonal codes, the access point may distinguish asignal transmitted by the first station STA1 from a signal transmittedby the fourth station STA4. However, since the second station STA2 andthe third station STA3 use the identical orthogonal code to cause acollision, the access point AP may not decode signals transmitted by thesecond station STA2 and the third station STA3.

The access point AP allocates channels to the first station STA1 and thefourth station STA4 on the basis of required information for channelallocation. In detail, the access point AP allocates the primary channelPrimary and the sixth secondary channel Secondary 6 to the first stationSTA1 and the first secondary channel Secondary 1 and the secondsecondary channel Secondary 2 to the fourth station. Since unable todecode signals transmitted by the second station STA2 and the thirdstation STA3, the access point AP does not allocate channels to thesecond station STA2 and the third station STA3.

The access point AP transmits a CTS frame to the first station STA1 andthe fourth station STA4 through channels respectively allocated thereto(operation S1402).

The first station STA1 and the fourth station STA4 transmit data throughchannels respectively allocated thereto. At this point, the fourthstation STA4 transmits dummy data until transmission by the firststation STA1 will be completed, even after data transmission by its ownwas terminated. At this point, a detailed transmission operation of thefourth station STA4 may be the same as the embodiment described above.In addition, the first station STA1 independently uses two allocatedchannels to transmit data. In detail, the first station STA1 transmitstwo pieces of data having different sizes through two respectivechannels allocated by the access point AP. At this point, the firststation STA1 transmits dummy data through the six secondary channelSecondary 6 through which data transmission was already terminated.

The access point AP transmits respective ACK frames to the first stationSTA1 and the fourth station STA4, after receiving data therefrom.

The method for notifying, by the first wireless communication terminal,the second wireless communication terminal of the access time to thefirst wireless communication terminal has been described before. Inparticular, the method for notifying, by the first wirelesscommunication terminal, the second wireless communication terminal ofthe access period to the first wireless communication terminal has beendescribed before. However, there may be a clock synchronizationdifference between the plurality of second wireless communicationterminals. In addition, there is a concern that the access time of eachof the plurality of second wireless communication terminals variesaccording to a channel occupancy situation of an adjacent BSS.Accordingly, a method is required to ensure that the plurality of secondwireless communication terminals simultaneously attempt to access thefirst wireless communication terminal. A description thereabout will beprovided in relation to FIG. 15 .

FIG. 15 shows that the plurality of stations according to an embodimentof the present invention transmit data to the access point on the basisof a trigger frame through which the plurality of stations triggeruplink transmission.

The first wireless communication terminal may transmit, to the secondwireless communication terminal, a trigger frame for triggering amultiple access to the first wireless communication terminal by thesecond wireless communication terminal. In detail, the first wirelesscommunication terminal may transmit the trigger frame to the secondwireless communication terminal in a constant period. In anotherdetailed embodiment, the first wireless communication terminal maytransmit the trigger frame to the second wireless communicationterminal, after a certain time passes from when having received a framefrom the second wireless communication terminal. At this point, thetrigger frame may comply with an RTS frame format. In detail, the firstwireless communication terminal may set, as a specific address, a valueof an RA field indicating a receiver address in the RTS frame, andtransmit the RTS frame to the plurality of second wireless communicationterminals. At this point, the specific address is to indicate an uplinkaccess and may be a broadcast address designated in advance.

The second wireless communication terminal having received the triggerframe transmits required information for channel allocation to the firstwireless communication terminal. In detail, after a certain time fromwhen the trigger frame has been transmitted, the second wirelesscommunication terminal may transmit required information for channelallocation to the first wireless communication terminal. At this point,the certain time may be a short inter-frame space (SIFS) defined in802.11 standards.

Thereafter, operations of the first and second wireless communicationterminals may be the same as the embodiments described above.

In an embodiment of FIG. 15 , the access point AP transmits a triggerframe for triggering multiple uplink accesses to a plurality of stations(operation S1501).

The first station STA1, the second station STA2, the third station STA3,and the fourth station STA4, which have received the trigger frame,respectively transmit required information for channel allocation to theaccess point AP using different orthogonal codes (operation S1502).

Then, operations of the access point AP, the first station STA1, thesecond station STA2, the third station STA3, and the fourth station STA4may be the same as described in relation to the embodiment of FIG. 13 .

Descriptions about that the first wireless communication terminalefficiently determines channels to be allocated to the plurality ofwireless communication terminals will be provided in relation to FIGS.16 and 17 .

FIG. 16 shows a basic service set including the plurality of stationsand the access point according to an embodiment of the presentinvention.

Channel circumstances sensed by each of the first wireless communicationterminal and the plurality of second wireless communication terminalsmay be different. Accordingly, when channels are respectively allocatedto the plurality of second wireless communication terminals inconsideration of only channel states sensed by the first wirelesscommunication terminal, the first wireless communication terminal mayallocate channels causing a collision with a wireless communicationterminal in another BSS to the plurality of second wirelesscommunication terminals. Such a situation will be described in relationto an embodiment of FIG. 16 .

In the embodiment of FIG. 16 , the access point AP senses, as idlechannels, the primary channel Primary, the first secondary channelSecondary 1, the second secondary channel Secondary 2, the thirdsecondary channel Secondary 3, and the sixth secondary channel Secondary6. However, the first station senses, as idle channels, the primarychannel Primary, the fourth secondary channel Secondary 4, the fifthsecondary channel Secondary 5, and the sixth secondary channel Secondary6. In addition, the second station STA2 senses, as idle channels, theprimary channel Primary, the first secondary channel Secondary 1, thefifth secondary channel Secondary 5, the sixth secondary channelSecondary 6, and a seventh secondary channel Secondary 7. In addition,the third station STA3 senses, as idle channels, the primary channelPrimary, the first secondary channel Secondary 1, the second secondarychannel Secondary 2, the fifth secondary channel Secondary 5, and thesixth secondary channel Secondary 6. In addition, the fourth stationSTA4 senses, as idle channels, the primary channel Primary, the firstsecondary channel Secondary 1, the second secondary channel Secondary 2,the third secondary channel Secondary 3, and the seventh secondarychannel Secondary 7.

At this point, when the access point allocates the second secondarychannel Secondary 2 to the first station STA1, the first secondarychannel Secondary 3 to the second station STA2, the primary channelPrimary to the third station STA3, and the sixth secondary channelSecondary 6 to the fourth station STA4, the remaining stations exceptthe third station may not use the allocation channels. Therefore, thefirst wireless communication terminal is required to respectivelyallocate channels to the second wireless communication terminals inconsideration of channel states sensedsens by the plurality of secondwireless communication terminals. A description thereabout will beprovided in relation to FIG. 17 .

FIG. 17 shows that the plurality of stations according to an embodimentof the present invention transmit data to the access point, when idlechannels sensed by the plurality of stations are different from thosesensed by the access point.

As described above, the second wireless communication terminal maytransmit channel access map information indicating a channel with whichthe first wireless communication terminal desires to be allocated. Atthis point, the channel access map information may include informationon an idle channel sensed by the second wireless communication terminal.

The first wireless communication terminal may allocate a channel to thesecond wireless communication on the basis of an idle channel sensed bythe second wireless communication terminal and the channel access mapinformation received from the second wireless communication terminal. Indetail, when the first wireless communication terminal senses any onechannel as being idle and the channel access map information indicatesthe corresponding channel to be idle, the first wireless communicationterminal may allocate the corresponding channel to the second wirelesscommunication channel.

In addition, the second wireless communication terminal may transmitrequired information for channel allocation through every channeldetermined to be idle by the second wireless communication terminal. Inthis case, the first wireless communication terminal may determine whichchannel is sensed to be idle by the second wireless communicationterminal without the channel access map information. Accordingly, thefirst wireless communication terminal may allocate, to the secondwireless communication terminal, a channel through which the secondwireless communication terminal transmits required information forchannel allocation and which is determined to be idle by the firstwireless communication terminal.

The first wireless communication terminal transmits a frame indicating achannel allocated to the second wireless communication terminal. Whenthe required information for channel allocation described above does notinclude an identifier or an address of the second wireless communicationterminal, a receiver address in the frame indicating the channelallocated to the second wireless communication terminal may be an indexof an orthogonal code used by the second wireless communicationterminal. In another detailed embodiment, a receiver address of a frameindicating a channel allocated to the second wireless communicationterminal may be an address value designated in advance according to theindex of the orthogonal code used by the second wireless communicationterminal.

In the embodiment of FIG. 17 , the first station STA1 transmits requiredinformation for channel allocation to the access point AP through theprimary channel Primary, the first secondary channel Secondary 1, thesecond secondary channel Secondary 2, the third secondary channelSecondary 3, and the seventh secondary channel Secondary 7 (operationS1701). In addition, the second station STA2 transmits requiredinformation for channel allocation to the access point AP through theprimary channel Primary, the first secondary channel Secondary 1, thefifth secondary channel Secondary 5, the sixth secondary channelSecondary 6, and the seventh secondary channel Secondary 7 (operationS1701). In addition, the third station STA3 transmits requiredinformation for channel allocation to the access point AP through theprimary channel Primary, the first secondary channel Secondary 1, thesecond secondary channel Secondary 2, the fifth secondary channelSecondary 5, and the sixth secondary channel Secondary 6 (operationS1701). In addition, the fourth station STA4 transmits requiredinformation for channel allocation to the access point AP through theprimary channel Primary, the first secondary channel Secondary 1, thesecond secondary channel Secondary 2, and the third secondary channelSecondary 3 (operation S1701).

The access point AP allocates respective channels to the first stationSTA1, the second station STA2, the third station STA3 and the fourthstation STA4 on the basis of channels through which the first stationSTA1, the second station STA2, the third station STA3 and the fourthstation STA4 transmit required information for channel allocation andchannels determined to be idle by the access point AP. In detail, in theembodiment of FIG. 17 , the access point AP senses, as idle channels,the primary channel Primary, the first secondary channel Secondary 1,the second secondary channel Secondary 2, and the sixth secondarychannel Secondary 6. Accordingly, the access point AP allocates theprimary channel Primary to the first station STA1, the first secondarychannel Secondary 1 to the second station STA2, the secondary channelSecondary 2 to the fourth station STA4, and the sixth secondary channelSecondary 6 to the third station STA3.

The access point AP respectively transmits a CTS frame to the firststation STA1, the second station STA2, the third station STA3, and thefourth station STA4 through channels respectively allocated thereto.

Then the operations of the access point AP and the stations may be thesame as the embodiments described above.

FIG. 18 shows that the plurality of stations according to an embodimentof the present invention transmit data to the access point inconsideration of a station that does not support the embodiment of thepresent invention.

When the plurality of second wireless communication terminals access thefirst wireless communication terminal in the way of the above-describedembodiments, there may be a problem of a compatibility with a wirelesscommunication terminal that does not support the embodiments of thepresent invention. For example, when not undergoing a backoff processaccording to a contention procedure while accessing the first wirelesscommunication terminal, there is a concern that the second wirelesscommunication terminal occupies unconditional superiority in channel usecontention with wireless communication terminals that do not support theembodiments of the present invention. Accordingly, the second wirelesscommunication terminal may access the first wireless communicationterminal through the remaining channels except the primary channel. Indetail, the second wireless communication terminal may transmit requiredinformation for channel allocation to the first wireless communicationterminal through the remaining channels except the primary channel. In adetailed embodiment, the second wireless communication terminal maytransmit the required information for channel allocation to the firstwireless communication terminal through the remaining channels exceptthe primary channel by using an orthogonal code.

In addition, when the wireless communication terminal that does notsupport the embodiments of the present invention transmits a frame tothe first wireless communication terminal through the primary channel,it is efficient that the first wireless communication terminalsimultaneously performs processes on the second wireless communicationterminal and the wireless communication terminal that does not supportthe embodiments of the present invention. For example, when the wirelesscommunication terminal that does not support the embodiments of thepresent invention transmits an RTS frame to the first wirelesscommunication terminal, it is efficient that the first wirelesscommunication terminal simultaneously transmits the CTS frame to thesecond wireless communication terminal and the wireless communicationterminal that does not support the embodiments of the present invention.However, since the wireless communication terminal that does not supportthe embodiments of the present invention transmits a frame afterundergoing a backoff process, a time for transmitting the frame may bedelayed. Accordingly, in consideration of this, the second wirelesscommunication terminal may transmit required information for channelallocation to the first wireless communication terminal and then wait acertain time. In another detailed embodiment, in consideration of this,the second wireless communication terminal may transmit the requiredinformation for channel allocation to the first wireless communicationterminal and then perform subsequent operations when there is no frametransmission through the primary channel for a certain time.

In the embodiment of FIG. 18 , the first station, the second station,the third station, and the fourth station transmit the requiredinformation for channel allocation through the secondary channels exceptthe primary channel and wait a certain time.

While the first station, the second station, the third station, and thefourth station wait, the wireless communication terminal that does notsupport the embodiments of the present invention transmits the RTS framethrough the primary channel.

The access point AP respectively transmits the CTS frame to the firststation, the second station, the third station, and the fourth stationthrough channels respectively allocated thereto.

In addition, at the same time, the access point AP transmits the CTSframe through the primary channel to the wireless communication terminalthat does not support the embodiments of the present invention.

In this way, since stations supporting the embodiments of the presentinvention transmit required information for channel allocation and thenwait, the access point AP may simultaneously perform transmission on thewireless communication terminal that does not support the embodiments ofthe present invention and transmission on the station supporting theembodiments of the present invention.

When the second wireless communication terminals simultaneously accessthe first wireless communication terminal, a processing amount of thefirst wireless communication terminal becomes several times that of acase where any one of the second wireless communication terminalsaccesses the first wireless communication terminal. Accordingly, thereoccurs a problem that a processing time of the first wirelesscommunication terminal increases and an interval between frames becomesexcessively large. When the interval between frames becomes excessivelylarge, there is a concern that a wireless terminal not currentlyparticipating in communication with the first wireless communicationterminal accesses a channel currently in use. Accordingly, a method isrequired which may reduce a processing burden on the first wirelesscommunication terminal, which is doubled by a multiple access.

FIG. 19 shows operations of the plurality of stations in considerationof a case where a channel allocation processing time by the access pointaccording to an embodiment of the present invention is delayed.

The second wireless communication terminal may transmit dummy data aftertransmitting any one frame to the first wireless communication terminal.In detail, the second wireless communication terminal may transmit up toan FCS field of any one frame to the first wireless communicationterminal and then transmit dummy data. As described above, such dummydata may be referred to as a busytone. In detail, the second wirelesscommunication terminal may transmit a frame including requiredinformation for channel allocation to the first wireless communicationterminal and then transmit dummy data. In addition, the second wirelesscommunication terminal may transmit a data frame including data to thefirst wireless communication terminal and then transmit dummy data. In adetailed embodiment, the second wireless communication terminal maytransmit dummy data after a certain time passes from when havingtransmitted a frame to the first wireless communication terminal. Atthis point, the certain time may be an SIFS defined in 802.11 standards.Through this, the first wireless communication terminal may have a timefor processing while dummy data is transmitted. In addition, anotherterminal that does not participate in transmission may be prevented fromaccessing the corresponding channel.

The second wireless communication terminal may repeatedly transmit anidentical frame to the first wireless communication terminal. In detail,the second wireless communication terminal may repeatedly transmit aframe including required information for channel allocation to the firstwireless communication terminal. In addition, the second wirelesscommunication terminal may repeatedly transmit a frame including data tothe first wireless communication terminal. At this point, the firstwireless communication terminal may ignore a repeatedly received frame.Through this, the first wireless communication terminal may have a timefor processing. In addition, another terminal that does not participatein transmission may be prevented from accessing the correspondingchannel.

In an embodiment of FIG. 19(a), the first station STA1, the secondstation STA2, the third station STA3, and the fourth station STA4respectively transmit frames including required information for channelallocation to the access point AP using different orthogonal codes. Atthis point, the first station STA1, the second station STA2, the thirdstation STA3, and the fourth station STA4 transmit two times more theframe including the required information for channel allocation to theaccess point AP (operation S1901). The access point AP ignores secondand third frames received after a frame including required informationfor channel allocation has been received at first. Through this, theaccess point AP secures a processing time for allocating channels to thefirst station STA1, the second station STA2, the third station STA3, andthe fourth station STA4.

The access point AP transmits a CTS frame to the first station STA1, thesecond station STA2, the third station STA3, and the fourth station STA4through channels respectively allocated thereto.

In an embodiment of FIG. 19(b), the first station STA1, the secondstation STA2, the third station STA3, and the fourth station STA4respectively transmit frames including required information for channelallocation to the access point AP by using different orthogonal codes.

The first station STA1, the second station STA2, the third station STA3,and the fourth station STA4 transmit the frame including the requiredinformation for channel allocation to the access point AP and thentransmit dummy data thereto (operation S1902). In detail, the firststation STA1, the second station STA2, the third station STA3, and thefourth station STA4 transmit the dummy data to the access point AP afteran SIFS from when transmitting the frame including the requiredinformation for channel allocation thereto. Through this, the accesspoint AP secures a processing time for allocating channels to the firststation STA1, the second station STA2, the third station STA3, and thefourth station STA4.

The access point AP respectively transmits the CTS frame to the firststation STA1, the second station STA2, the third station STA3, and thefourth station STA4 through channels respectively allocated thereto.

FIG. 20 is a ladder diagram showing an operation in which the secondwireless communication terminal according to an embodiment of thepresent invention transmits data to the first wireless communicationterminal.

The first wireless communication terminal 300 transmits a frameincluding information on an access method to the second wirelesscommunication terminal 500 (operation S2001).

As described above, the information on the access manner may include aplurality of access methods for allowing the plurality of secondwireless communication terminals 500 to perform accesses using a certaincommunication manner. In addition, the information on the access mannermay include information on an orthogonal code used for accessing, by thesecond wireless communication terminals 500, the first wirelesscommunication terminal. In detail, the information on the orthogonalcode may include information on an orthogonal code set including aplurality of orthogonal codes. In another detailed embodiment, theorthogonal code may be designated in advance to the second wirelesscommunication terminal 500. At this point, the second wirelesscommunication terminal 500 may be allocated with an orthogonal code asan association identifier for identifying an association with the firstwireless communication terminal 400 in an association process with thefirst wireless communication terminal 400. In this way, the secondwireless communication terminal 500 may access the first wirelesscommunication terminal 400 using an orthogonal code allocated theretowithout any separate process.

In addition, the information on the access manner may includeinformation on a time for accessing, by the second wirelesscommunication terminal 500, the first wireless communication terminal400, as described above. In detail, the information on the access mannermay include information on a period that the second wirelesscommunication terminal 500 accesses the first wireless communicationterminal 400. In a detailed embodiment, the information on the accessmanner may include the number of times that the second wirelesscommunication terminal 500 accesses the first wireless communicationterminal 400 for a certain period.

In another detailed embodiment, the first wireless communicationterminal 400 may transmit, to the second wireless communication terminal500, a frame for triggering an access by the second wirelesscommunication terminal 500 without transmitting a detailed access timeas described above. Through this, even when clocks of the secondwireless communication terminals 500 are not synchronized, uplink accesstimes of the plurality of second wireless communication terminals may besynchronized.

The second wireless communication terminal 500 acquires information onthe access method on the basis of a frame including information on theaccess manner (operation S2003). The second wireless communicationterminal 500 may acquire information on the orthogonal code used for theaccess to the second wireless communication 500 on the basis of theframe including the information on the access method. The secondwireless communication terminal 500 may acquire information on theaccess time to the second wireless communication 500 on the basis of theframe including the information on the access method.

The second wireless communication terminal 500 accesses the firstwireless communication terminal 400 on the basis of information on theaccess method (operation S2005).

In detail, the second wireless communication terminal 500 may randomlyselect any one of a plurality of access manners and transmit data to thefirst wireless communication terminal 400 on the basis of the selectedaccess method. In addition, the second wireless communication terminal500 may transmit data to the first wireless communication terminal 400on the basis of information on the orthogonal code. In addition, thesecond wireless communication terminal 500 may transmit data to thefirst wireless communication terminal 400 on the basis of information onthe access time.

In addition, the second wireless communication terminal 500 may accessthe first wireless communication terminal 400 using remaining channelsexcept the primary channel. Through this, compatibility and channelcontention fairness with a wireless communication terminal that does notsupport the embodiments of the present invention may be ensured.

Furthermore, the second wireless communication terminal 500 may beallocated with a channel from the first wireless communication terminal400 by transmitting required information for channel allocation thereforon the basis of the information on the access manner. The secondwireless communication terminal 500 may transmit data to the firstwireless communication terminal 400 through the allocated channel.

In addition, the second wireless communication terminal 500 may transmitthe required information for channel allocation therefor on the basis ofthe information on the access method. In detail, the requiredinformation for channel allocation may include information forindicating the size of data to be transmitted by the second wirelesscommunication terminal. In addition, the required information forchannel allocation may include an identifier for identifying the secondwireless communication terminal 500. At this point, the identifier foridentifying the second wireless communication terminal 500 may be an AIDor a partial AID for identifying an association with the first wirelesscommunication terminal 400. In addition, the required information forchannel allocation may include channel access map information indicatinga channel with which the second wireless communication terminal desiresto be allocated. At this point, the channel access map information mayinclude information on an idle channel sensed by the second wirelesscommunication terminal 500. In a detailed embodiment, the secondwireless communication terminal 500 may transmit the requiredinformation for channel allocation therefor on the basis of theinformation on the access time. In a detailed embodiment, the secondwireless communication terminal 500 may transmit the requiredinformation for channel allocation therefor on the basis of theinformation on the orthogonal code.

The first wireless communication terminal 400 may transmit a frameindicating a channel allocated to the second wireless communicationterminal 500 on the basis of the required information for channelallocation for the second wireless communication terminal 500. Indetail, the first wireless communication terminal 400 may allocate thechannel to the second wireless communication terminal on the basis ofthe required information for channel allocation for the second wirelesscommunication terminal 500. In a detailed embodiment, the first wirelesscommunication terminal 400 may allocate the channel to the secondwireless communication terminal 500 on the basis of the size of data tobe transmitted by the second wireless communication terminal 500. Inanother detailed embodiment, the first wireless communication terminal400 may allocate the channel to the second wireless communicationterminal 500 on the basis of information on an idle channel sensed bythe second wireless communication terminal 500 and an idle channelsensed by the first wireless communication terminal. For example, whenthe first wireless communication terminal senses any one channel as anidle channel and the channel access map information indicates thecorresponding channel as being idle, the wireless communication terminal400 may allocate the corresponding channel to the second wirelesscommunication channel 500. Through this, the first wirelesscommunication terminal 400 may solve a hidden node problem and raise anefficiency of channel allocation.

In detail, the first wireless communication terminal 400 may transmit aframe indicating the channel allocated to the second wirelesscommunication terminal 500 through the channel allocated to the secondwireless communication terminal 500. At this point, the frame indicatingthe channel allocated to the second wireless communication terminal 500may include information indicating a time available for datatransmission by the second wireless communication terminal 500. At thispoint, the time available for data transmission may be a time commonlyapplied to the plurality of second wireless communication terminals 500.Accordingly, the time available for the data transmission may bedetermined based on the longest time among times required for datatransmission by the plurality of second wireless communication terminals500. At this point, the time available for data transmission may betransmitted as a duration field value of the frame indicating thechannel allocated to the second wireless communication terminal 500.Accordingly, the duration field value of the frame indicating thechannel allocated to the second wireless communication terminal may bedetermined based on a required transmission time of the largest dataamong transmission pieces of data of the plurality of second wirelesscommunication terminals 500. In addition, the frame indicating thechannel allocated to the second wireless communication terminal 500 maybe a CTS frame.

The first wireless communication terminal 400 may transmit data to thefirst wireless communication terminal 400 on the basis of the frameindicating the allocated channel. At this point, the first wirelesscommunication terminal 400 may transmit data to the first wirelesscommunication terminal 400 through the channel indicated by the frameindicating the allocated channel.

In addition, the second wireless communication terminal 500 may transmitdummy data to the first wireless communication terminal 400. In detail,the second wireless communication terminal 500 may transmit the dummydata to the first wireless communication terminal 400. In detail, thesecond wireless communication terminal may transmit up to an FCS fieldof any one frame and then transmit the dummy data to the first wirelesscommunication terminal. In a detailed embodiment, the second wirelesscommunication terminal 500 may transmit a frame including the requiredinformation for channel allocation and then transmit the dummy data tothe first wireless communication terminal. In another detailedembodiment, the second wireless communication terminal 500 may transmita data frame including data and then transmit the dummy data to thefirst wireless communication terminal 400. For example, the secondwireless communication terminal 500 may transmit the dummy data to thefirst wireless communication terminal 400, after a certain time passesfrom when having transmitted a frame to the first wireless communicationterminal 400. Through this, the first wireless communication terminal400 has a time for processing, while the dummy data is transmitted. Inaddition, another wireless communication terminal that does notparticipate in transmission may be prevented from accessing thecorresponding channel.

The second wireless communication terminal 500 may repeatedly transmitan identical frame to the first wireless communication terminal 400. Indetail, the second wireless communication terminal 500 may repeatedlytransmit the frame including the required information for channelallocation to the first wireless communication terminal 400. The secondwireless communication terminal 500 may repeatedly transmit a frameincluding data to the first wireless communication terminal 400. At thispoint, the first wireless communication terminal 400 may ignore therepeatedly received frame. Through this, the first wirelesscommunication terminal 400 has a time for processing. In addition,another terminal that does not participate in transmission may beprevented from accessing the corresponding channel.

As described above, although wireless LAN communication is exemplarilydescribed for the present invention, the present invention is notlimited thereto and may be identically applied to another communicationsystem such as cellular communication. In addition, although the method,device and system of the present invention are described in relation tospecific embodiments, the configuration elements, a part of or theentirety of operations of the present invention may be implemented usinga computer system having general purpose hardware architecture.

In the foregoing, features, structures, or effects described inconnection with embodiments are included in at least one embodiment, andare not necessarily limited to one embodiment. Furthermore, theexemplified features, structures, or effects in various embodiments canbe combined and modified by those skilled in the art. Accordingly,contents in connection with these combination and modification should beconstrued to fall in the scope of the present invention.

Although embodiments have been described with reference to a number ofillustrative embodiments thereof, it should be understood that numerousother modifications and embodiments can be devised by those skilled inthe art that will fall within the spirit and scope of the principles ofthe present invention. For example, variations and modifications in thecomponent parts and/or arrangements, alternative uses will also beapparent to those skilled in the art. In addition, differences relatedto such modifications and application should be interpreted to be withinthe scope of the present invention defined in the appended claims.

1-20. (canceled)
 21. A wireless communication terminal comprising: atransceiver; and a processor, wherein the processor is configured to:receive, using the transceiver, a first trigger frame for triggeringmultiple access to a base wireless communication terminal, transmit, ata designated time, information on whether each of channels is sensed tobe idle by the wireless communication terminal at the designated time tothe base wireless communication terminal simultaneously with atransmission of information on whether each of channels is sensed to beidle by one or more other wireless communication terminals from the oneor more other wireless communication terminals, wherein the designatedtime is determined based on a SIFS (short inter-frame space) and a timewhen the first trigger frame has been received, receive a second triggerframe including information on a channel allocated to the wirelesscommunication terminal, obtain the information on the channel allocatedto the wireless communication terminal from the second trigger frame,and access the base communication terminal through the channel allocatedto the wireless communication terminal.
 22. The wireless communicationterminal of claim 21, wherein the processor is configured to transmitthe information on whether each of channels is sensed to be idle by thewireless communication terminal using an orthogonal code.
 23. Thewireless communication terminal of claim 22, wherein the processor isconfigured to randomly select any one of a plurality of orthogonalcodes, and transmit the information on whether each of channels issensed to be idle by the wireless communication terminal using theselected orthogonal code.
 24. An operation method of a wirelesscommunication terminal included in a plurality of wireless communicationterminals, the operation method comprising: receiving a first triggerframe for triggering multiple access to a base wireless communicationterminal, transmitting, at a designated time, the information on whethereach of channels is idle at the designated time to the base wirelesscommunication terminal simultaneously with a transmission of informationon whether each of channels is sensed to be idle by one or more otherwireless communication terminals from the one or more other wirelesscommunication terminals, wherein the designated time is determined basedon a SIFS (short inter-frame space) and a time when the first triggerframe has been received, receiving a second trigger frame comprisinginformation including information on a channel allocated to the wirelesscommunication terminal; obtaining the information on the channelallocated to the wireless communication terminal from the second triggerframe; and accessing the base communication terminal through the channelallocated to the wireless communication terminal, wherein the basewireless communication terminal is any one wireless communicationterminal different from the plurality of wireless communicationterminals.
 25. The method of claim 24, wherein transmitting, at thedesignated time, the information on whether each of channels is idle atthe designated time to the base wireless communication terminalcomprises transmitting the information on whether each of channels issensed to be idle by the wireless communication terminal using anorthogonal code.
 26. The method of claim 24, wherein the transmittingthe information on whether each of channels is sensed to be idle by thewireless communication terminal using an orthogonal code comprisesrandomly selecting any one of a plurality of orthogonal codes, andtransmitting the information on whether each of channels is sensed to beidle by the wireless communication terminal using the selectedorthogonal code.